Wednesday 24 September 2008

The ozone hole - information and data

In the New Scientist, an article about how NASA failed to spot the ozone hole.

The story has lots of strands, but picking out one element:
According to Pawan Bhartia, who was processing the satellite data [what the computer software collecting the data] did was "flag it up" - identifying it as unreliable. The computer, he told New Scientist, then substituted "fill values" that it thought more likely. The effect was [...] the "unreliable" data was buried and the researchers had no reason to think anything was amiss.
One of the standard things my children have been taught at school - one the things they'll get marks in the course-work for - is recognising spurious data points in graphs that you should disregard. Usually that's right, of course ("of course"? or "I suppose"?), but also risks throwing out the most important data - the data that actually gives the most information. Someone once told me that among the data that Millikan found, and disregarded, in his wonderful oil-drop experiment were some measurements that returned a value of 1/3 that of the charge of an electron - ie the charge of a quark! I don't think anyone seriously believes he'd isolated a quark (my understanding is that it isn't possible), but wouldn't that have been nice!

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